The science of climate change and the coast

Gold Coast, Qld. Photo Credit: Bruce Miller The Australian coast is a dynamic place. In the past, major changes have occurred in sea levels, habitats and in the shape of the coastline.

Climate records indicate that during previous geological timeframes (many millions of years ago) sea levels in Australia have risen and fallen in response to changes in the climate. For example, during previous ice ages sea levels were up to 4-6 metres higher than today and the Australian shoreline was up to 500 kilometres inland.

However in the last 6,000-7,000 years, sea levels around Australia have been relatively stable. The majority of Australia's coastal landforms and ecosystems and more recently, human settlements have persisted without large scale change. Those conditions are now changing.

Increased concentrations of greenhouse gases in the atmosphere (such as CO2) from human activity are leading to a warming of the earth's climate system: the atmosphere, land and oceans. During the past 100 years, global average temperatures have increased by over 0.7oC. Since 1910, Australia's average temperature has risen by almost 1oC, and 2009 marked the end of our hottest decade on record.

As the climate system warms, heat from the atmosphere is absorbed by the oceans. This warming of the oceans leads to rising sea levels because the oceans expand as they warm and because additional water enters the oceans when land ice from glaciers and ice caps melts. The global rate of sea level rise for the 20th century was about 1.7 mm per year. In recent decades the rate of sea level rise has accelerated. Since 1993 global sea levels have risen by about 3.4 mm per year.

As well as rising sea levels and higher temperatures, coastal areas will also experience changes in rainfall patterns and in the frequency and size of storms and cyclones. Together these will lead to increasing risks of bushfires, flooding, strong winds and erosion of soft shorelines.

These climate risks may have significant impacts on Australia's coastal communities, industries and natural ecosystems. They may also affect the delivery of essential services and associated infrastructure such as road and rail networks, power supply and water/utility networks. The risks of sea level rise may reach beyond the coast itself. Flooding may impact on areas some distance inland, for example along estuaries, rivers, lakes or lagoons.

We still have time to prepare for the impacts of climate change, but we need to start now.

Read about the risks to coastal settlements, infrastructure and ecosystems (and access sea level rise maps)

Find out more about climate change science and rising sea levels

If you have questions about coastal climate change please contact the Department of Climate Change and Energy Efficiency: enquiries@climatechange.gov.au

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